EVS27
Barcelona, Spain, November 17-20, 2013
An E.Bike Design for the Fourth Generation Bike-Sharing
Services
Ricardo Meireles1, Jose Silva1, Alexandre Teixeira1, Bernardo Ribeiro1
1
CEIIA – Centro para a Excelência e Inovação na Indústria Automóvel
Rua Eng. Frederico Ulrich, 2650 (Tecmaia), 4470-605 Maia, Portugal
Abstract
Bicycle sharing systems have proven their value towards urban sustainable mobility. Appropriate design of
bikes for this application is fundamental for bike-sharing systems viability. A new e.Bike was designed for
the specific application of bike-sharing. This bike model has a significant number of new features that
improve the user experience through an adequate position of motor, as well as the addition of new
functions such as the locking of the bike and rider safety. At the same time the reduction of number of parts
and the use of new materials, contribute to the viability of this e.Bike model and the associated bikesharing system.
Keywords: Bicycle, Fleet, Intelligent, Mobility, Safety
1
Introduction
Bicycle sharing systems have proven their value
towards urban sustainable mobility. Although it
looks a natural simple concept, implementation
of a reliable and sustainable system has proven to
be difficult and at the same time challenging. A
long journey has been done since the first system
implemented during the 60s in Amsterdam, with
the so called “white bikes” [1]. Since that time
several innovating issues have been introduced in
bike-sharing systems. These systems have
evolved
through
several
technological
generations that have been leading to the increase
of robustness, and recent inclusion of
intelligence. The first generation included plain
bikes without dropping stations, which do not
provide enough control, security or fleet
management capability.
2nd generation brought the implementation of
dedicated bicycle design feat to withstand
intensive use and misuse. These include stronger
frames and components, together with the
introduction of solid rubber tires. Also
implemented in the 2nd generation were specific
picked up and return locations.
The 3rd generation added costumer tracking
capability to discourage theft and misuse. The
implemented systems included smart cards or
mobile phone access, electronic lock, on-board
computers and telecommunication systems.
Bike –sharing future generation (4th) must address
the efficiency of the system, both from the
operator and costumer perspective. Also important
on future bike-sharing systems is the improvement
of user friendly features. One of the greatly
expected features in this category is the
implementation of electric bicycles on sharing
systems, allowing users to ride longer, on hilly
terrains with less effort. From the operator point of
view, the 4th generation includes an IT
(Information Technology) system to improve bike
distribution on the dropping stations and new
business models.
In order to be used in 4th generation bike-sharing
systems, new bikes need to be developed in order
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to address all issues already included on the first
three generations and the specific requirements
that allow the implementation of the 4th
generation, where electric powertrain is included,
as well as integration with smart management
system, keeping the complete system affordable
for the user as well as for the operator.
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3- Cost efficiency - Design should target a low
cost, low volume production that could be easily
upgraded for medium volumes if needed. Thus,
material selection should focus on cost-efficient
solutions that require low raw material cost, low
cost for production equipment and tooling and
reduced costs for processing.
Requirements definition
The development of an e-bike for a bike-sharing
system requires that two main points of concern
have to be considered. First is the need of the
operator focus on a reliable, simple, efficient,
sustainable but profitable system. On the other
hand, are the features that both bicycle riders and
general citizens appreciate. Achieving the
balance between those two points is critical for
the success of the system, mainly when the gold
is to design a bike system to be used in many
different “hands”, and therefore needs to be
robust, yet trendy and with enough enchantment
to create the desire to be used.
A deep analysis was performed in order to
understand the requirements applied to these
bikes. These requirements were divided into 3
different categories:
1- Usability – The bike should include an electric
powertrain for riding assistance, which includes a
motor, a battery pack with enough energy storage
capacity to allow at least two consecutives uses
without running out of energy, for the average
riding times on such systems.
On the intelligent features, automatic movements
should be included in several functions in order
to reduce the human intervention and with this,
also reduce bike components.
On the safety point of view, new features should
be included in order to improve the user safety
when riding the bike, considering specially the
interaction with the cars and urban heavy
vehicles.
2- Design – Considering the use of motor and
battery pack, weight must be reduced on other
components and the structure itself, in order to
keep the bike with the same performance level
and energy consumption. Lean design is a must,
so that few components are integrated on the
bike. Other features need to be added, such as
safe design to avoid vandalism, theft and misuse.
From the aesthetic point of view it should be
trendy and with flat surfaces for publicity
exhibition.
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E.Bike development
The e.Bike development was performed focusing
on each requirement and defining technical
solutions.
3.1
Motor position
After the study of three types of possible motor
layouts (front wheel, rear wheel and crank shaft),
the crank shaft motor position was the selected
one. In an e.Bike is very usual to use, a front wheel
or a rear wheel motor, mainly due to the cost
factor, and simple installation and maintenance. In
fact, this solution is the most appropriate when
considering bikes for private use.
Figure 1: Crank shaft motor position
On a preliminary evaluation, the crank shaft motor
position could be considered not the ideal solution
due the fact that maintenance would be more
difficult to perform, because more components
need to be handled. However, for this same reason,
it is a good solution for an e.Bike sharing system,
once the motor is considered a valuable component
with a high risk to be vandalized or thieved.
Having the motor enclosed inside body panels (as
explained latter on chapter 3.6) is and additional
protection for this key component against
vandalism actions. In the particular design of this
e.Bike the motor, placed on the crank shaft, is
protected inside robust body panels. But, the crank
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shaft motor position was also chosen because this
solution allows a good user friendly experience,
since the power is provided directed on the crank
shaft, giving a comfortable control sensation to
the rider, similar to riding a conventional bike,
and thus more natural behaviour. The rider can
have a better and more natural control on the
power transmitted to the wheel with this type of
motor, also reducing the inertial and mechanical
lost associated with chain powered transmissions.
The selected motor is compatible with rear hub
gears, which makes it possible to be used
combining human power and electric power
motor.
3.2
Safety laser
Aiming towards the safety of the rider, a laser
line is added as an alert presence and bike
identification. This is a new trend among the
private bike market. This laser device with a very
small size and low weight, is mounted on the
back end of the rear dropout. This laser device is
protected under the body panels, and uses a laser
beam to project two red lines to each side of the
bike. Each red line projected on the pavement is
parallel to the longitudinal direction, giving to
the other users of the road, particularly
automobile drivers, a sense of the space they
need to allocate to the cyclist.
This allows other drivers to safely overcome the
riders by respecting safety distance with visual
reference. The laser red colour also helps to
increase the feeling of alert to other drivers.
This is a low cost device that can save the life of
cyclist, especially during night use.
Figure 2: Safety laser line.
3.3
Locking and charging system
An essential system of the bike sharing is the
coupling on the dock. Electric bike sharing, not
only needs to have a robust mechanism to firmly
lock the bike to the dock, but due to the fact that
the battery need to be charged, a system to connect
and perform charging simultaneously need to be
added.
Common ways to address this issue on current
electric bike sharing is either use detachable
batteries or use a connection cable for electric
charging. However, this is not a comfortable action
for a rider using a shared bike. The rider expects to
have a simple drop-and-leave behaviour, when
leaving the e.Bike on the docking station, and this
is more critical if we consider the metropolitan
user that in most of the time is in a rush to leave
the bike and pick-up next public transportation.
Thus a simple and user friendly system must be
built-in.
In order to address this issue, a system was
developed that allows with a single user
movement, to lock the bike in the docking station
and start charging. The system is composed by a
coupling mechanism fitted on the bike side and by
the respective nest on docking side. On the bike
frame the coupling mechanism was installed in the
bike head tube, for two main reasons - the first
related with ergonomics aspects – the rider can
dock the bike in a standing position even without
the need to off the bike, having a perfect eye
control on the fitting mechanism – the second
related with engineering aspects – the bike head
tube was designed to have a thickness and
geometry able to resist to vandalism torsion or
unauthorized tentative to remove the bike from the
docking, being a robust place to install the locking
triggers. The locking and charging system was
specially designed to be easily used by a nontrained person, hence both bike and docking
alignments angles were carefully selected in order
to compensate any terrain irregularity and allow
the correct orientation of coupling triggers.
On the bike side, there is a cap that protects the
electric plug from water and dust. This cap only
opens when the bike receives signal, trough the
intelligence box that is perfectly fitted on the dock,
preventing this way any risk of electric shock by
hiding the electric plugs. Only after receiving the
signal that the bike is perfectly fit and in final
locked position, the system starts to charge the
battery, and create the communication link
between the bike and the rest of the system.
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This is one of the most critical mechanisms in all
system, and must withstand abusive load for
vandalism scenarios, but most of all, should be a
user-friendly and intuitive system.
Figure 3: Locking and charging mechanism.
3.4
Bike Stem
3.5
Structural Validation
A bike-sharing system is by definition a bike that
must withstand very demanding use. In pursuit of
the highest safety level and to ensure the best
reliability, structural performance was evaluated
with Computer Aided Engineering (CAE)
simulations and Finite Element Analysis methods,
in order to comply with the safety requirements
and test methods defined in the European Standard
EN 14764 (City and trekking bicycles). A set of
simulations was made, considering steel and
aluminum components. Some examples of the
simulations performed were:
1) Steering assembly – Static strength and security
tests;
2) Frame and fork assembly – Impact test;
3) Frame - Fatigue test with pedaling forces;
4) Frame - Fatigue test with vertical force;
5) Fork intended to use with hub- or disc-brakes strength test.
Towards anti-vandalism features a dedicated
stem without visible screws was designed. This
solution applies a new assembly approach to the
handle bar and stem. This cover is also used to
protect the electric and braking cables. Looking
forward for multifunction components that could
also be seamless integrated in the e.Bike all
critical fixtures are hidden. It includes an internal
cable path protection, and also integrates the
basket fixture without visible screws.
This new bike stem, due to its shape, also allows
to achieve a more ergonomic upright position
suitable for long and relaxing ride.
Figure 5: CAE simulation
The structural stability was also accessed by means
of buckling analysis and some additional tests
were performed to ensure the assembly integrity in
the event of vandalism acts.
3.6
Figure 4: Bike stem without visible screws
Intelligence Box
An on-board computer provides real time
monitoring and control over the bicycle and
tracking during its use by combining sensorization,
calculation, and communication ability.
After evaluating current systems tracking ability
and typical vandalism misuse, one of the new
features proposed was the use of a 3 axis
accelerometer. This will allow the operator, among
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other applications, to identify if the bicycle is
being exposed to abusive use and as the
monitoring is done in real time, the bike-sharing
system operator may decide to act by sending a
warning to the user or limiting bicycle
performance. On board decisions towards misuse
can also be programed in the computer allowing
for example the e.Bike motor to be turn off when
abusive use is detected.
3.7
Body Panels
To achieve stylish design at low volume
production and low cost, plastic body panels
were designed, which also may be used as
publicity support during operation.
Figure 6: Plastic body panels
Producing plastic parts for low volume series is
always a challenge. DCPD-RIM was the selected
technology for this case. In this technology the
tooling used is simple and based on a single corecavity structure allowing this way to have a cost
efficient production, and to achieve body panels
with good perceived quality and at a sustainable
level of productions cost. [2]
Bike-share, can benefit from being a publicity
support that is in constant movement inside the
city area, and seen by large number of people. To
profit from this feature, flat body panels need to
be available on the bike to add publicity on. In
this bike-sharing system the body panels were
designed with a style language that permits the
use of publicity on the seat tube and down tube
panels, as they were designed with flat surfaces.
These panels also serve the purpose of protecting
the critical systems of the e.Bike, such as the
motor, battery and intelligence box.
The maintenance access to critical components,
is done through a non-visible system made by
clipping and screws placed on the bottom part of
the body. Panels are assembled in a specific order
that assure the correct protection to dust and water.
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Conclusions
There are three key issues that must be addressed
when developing a bike sharing system, they are
the operator, the user and the citizens that lives and
uses the city. Designing a sustainable system
requires two approaches, cost reduction, looking
for cost effective production processes, but also
requires add value design features, and both of
them can represent extra services for the operator
to charge or saving costs in maintenance.
A new e.Bike was designed for the specific
application of bike-sharing. This bike model has a
significant number of new features that improve
the user experience through an adequate position
of motor, as well as the addition of new functions
such as the locking of the bike. During the
development process new solutions were achieved
in terms of bike design that allows an improvement
in terms of components number reduction, system
security and monitoring. The use of new materials
such as DCPD allowed the introduction of body
panels at an adequate cost level giving the bike a
stylish shape and protecting critical bike
components.
Acknowledgments
The work described here above was funded
through the EU QCA project.
References
[1] DeMaio, Paul, “Bike-Sharing: History, Impacts,
Models of Provision, and Future”, Journal of Public
Transportation, Vol. 12, Nº4, pp. 41-56, 2009.
[2] Teixeira, Alexandre, Ribeiro, Bernardo, Use of
DCPD/RIM on exterior panels for the automotive
industry, RPD 2010 – Rapid Product Development,
Marinha Grande, Portugal, 2010.
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Authors
Ricardo Meireles, has been working
with CEIIA in product development
for 7 years on automotive components
and subsystems in both plastic and
metallic parts. Projects develop
include the NEXX SU bike Helmet
that uses a special design opening
mechanism, and a seat module for M1
vehicles with an hybrid structure of
injected plastic and metal stamp parts.
Regarding electric mobility has work
on Norwegian electric car Buddy M9
and the CEIIA MobiCar program.
Jose Silva - Licentiate in Mechanical
Engineering. He has 5 years’
experience in product development
participating and coordinating the
development of different systems and
modules for various OEM's, including
VW and McLaren. Alongside the
latest manufacturer, he attended as
team
management
regarding
subsystem design, packaging and
assembly.
Alexandre Teixeira, Head of Auto &
Mobility Unit. Polymer Engineer. Was
involved in more than 150 projects
related to the Aeronautic, Automobile,
Medical and Electronic on the last 10
year. Creator and coordinator of
projects on the area of technologies of
gas-assist injection systems, biomaterial injection (natural cork),
natural fibres. Presently he is
dedicated on the new mobility trends,
related with electric mobility systems,
in terms of new modules and systems
developments.
Bernardo Ribeiro holds a PhD in
Mechanical engineering (automotive)
and graduated with a Mechanical
Engineering Degree. Since 2003 he is
being
working
on
automotive
powertrain R&D. He joined CEIIA in
2009 and at the moment he is the R&D
coordinator
at
CEIIA,
with
responsibility
of
technological
intelligence, definition and supervising
of R&D projects.
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